Pyrometer tube



April 24:, 1945. 1 w, PERY 2,374,377

PYROMETER TUBE Filed April 5, 1943 INVENTORJ JM ika/30 PEECV.

5//5 firme/VU Patented Apr. 24, 1945 PYROMETER TUBE James Ward Percy,Jersey City, N. J., assignor to United States Steel Corporation ofDelaware, a

corporation of Delawarc Application April 5, 1943, Serial No. 481,90l

(c. rss- 4) 1 claim.

This invention is concemed with the problem of determining the heatingrate of a metal charge in a metal heating furnace. For example, thehot-roliing of steel slabs requires heating the slabs to a properhot-rolling temperature, this involving the necessity for determlninghow long the slabs should remain in the furnace used to i bring them tosuch a temperature, or, in other words, the heating rate of the. slabsin the furnace.

The principles of the invention are illustrated by the accompanyingdrawing in which: v

F gura 1 is a partial cross section of a. continuous slab heatingfurnace with the invention v in operation;

Figure 2 is an enlarged longitudinal section of a detail from Figure 1;

Figure'3 is an elevation of Figure 2;

Figura 4 is a side view of Figure 3; and

F'gure '5 is a cross section from the line V-V in Figure 4.

More specifically, this drawing shows a partial cross section of aconventional continuous steel slab heatingfurnace l having a hearth 2over which the slabs 3 are intermittently pushed transversely throughthe urnace, the furnace being provided with the usual series 'ofobservation ports 4 permitting observation of the slabs as they progressthrough the furnace. The various specific features involved are familiarto anyone skilled in the art.

Heretofore, the customary way of determining the heating rate of theslabsas they progress through the fumace has been to measure theexternal surfaces of the slabs as they pass'by the port 4, the dataobtained in this manner being used to regulate the temperature and timevalues of the slab heating cycle to assure the slabs reaching a properhot-rolling temperature just prior to their leaving the iumace.Frequently, the urnace is provided with an automatic photocell radiationpyrometer with its cell 5 sighted through a tube 5 on the slab surfacesat a position near the furnace slabexit, in order to determine that theslabs have in fact attained a hot-rolling temperature before they leavethe furnace.

The outlined procedure involves the problem that it has been impossibleto determine whether the slabs were heated throughout to the desiredtemperature, the heating rate of the slab surfaces being the only thingdetermined and this notproviding an adequately safe guide 'to theinternal heating rate of the slabs. That is to say, hot rolling requiresthe slabs to be heated throughout to a proper hot-rolling temperature(yet the prior art has provided only for determining the heating rate ofthe external slab sui-faces, this involving the necessity forcalculating the internal slab temperatures instead of knowing themdefinitely.

According to the present invention, when it is desired to determine theheating rate of the slabs, a hole is drilled to the geometrical centerof a representativ one of the slabs as at 6. This V hole is drilled fromthe side of the slab that passes opposite the ports 4 in such a mannerthat the hole attains axial alignment with these ports. As the slabpasses successively by the various ports a thermocouple is slid in thehole 6 to the geometrical center' 'of the slab and a temperature readingis obtained of the actual internal temperature of the slab, thisinvolving conventional use of the thermocouple so far as obtaining thetemperature value is concerned. In this fashion it is possible to obtainthe heating rate at spaced time intervals of the actual inside of theslab at a point where the heat has the most difiiculty of reaching.Preferably, the external heating rate is -determined in the conventionalfashion knowledge of the actual heating rate of the slab both extemallyand internally as it progresses through the furnace. Obviously, anyother furnace charge involving the same problem can be handled in thesame fashion, and the principies involved may be applied regardless ofwhether the furnace is of the continuous type 'or the charge remainsstationary in the furnace durin its heating. It is only :necessary tomeasure the internal temperature of the charge at spaced time intervalsto provide the information discussed. The resulting information may beused, for examples, to adjust the time and temperature values of theheating cycle, to test a' new furnace design, or to indicate that an oldfurnace needs redesigning.

Preferably, special equipment should be used in carrying out thisinvention. With this in mind, the thermocoupleis positioned in a quartztube 1 having a closed end 8 and with its other end open to permitpassage of the necessary leads to the thermocouple, these leads and thethermocouple not being illustrated because they may follow conventionaldesign. Heat-resisting cement 9 fastens the tube 'I concentricall'yinside a larger tube I 0 made of heat-resisting metal, such a !8-8 or25-42 chromium-nickel stainless steel, and having a tapered endextending beyond the closed end 8 of the quartz tube 'I so 2 as toprotect this relatively iragile part, the end H oi the tube o beingtapered to permit its easier guidance into' the hole in the slab. The

arrangement is such that the outside of the tube 'lis spaced from theinside of the tube o, in the interest of adequately protecting the tube'I from damage. the tube III having side openings oexposing the tube 'ldirectly to the slab heat. The tube I! is provided with a threaded end|2 opposite the end II and this threaded end is arranged in' screwthreaded engagement with a pipe Illb, also 'made of heat-resistingmetal. which is of adequate length to project the tube n to'thegeometrical center of the slab by way of the hole in the latter from aposition conveniently outside of the port I being used at the time.

A water-'cooled tubular jacket !3 is provided with a verticallyadjustable frame 'll carried by a wheeled carriage IS, this permittingthe jacket I! to be wheeled up to the port 4 and the jacket I: thenthrust through this port, 'the jacket !3 having a sufllciently largeinside passageway to permit projection therethroughot the pipe IIIcarried on the end of the pipe lub, the endof the jacket I: beingpositioned close to the side of the siab having the hoie 'so that thepipe Ilb is to get the thermocouple to the inside of the :lab

and withdraw it as quickly as is consistent with obtaining an accuratetemperature measure-` ment.

The quartz tube 'I is used to protect the thermocouple against thefumace atmosphere because it conducts heat with adequate rapidity.Actual use of equipment such as disclosed has shown that the disclosedprotective features for these parts are adequate to make its usecompletely practica1..

. I'clain:

'I'he'combinatio'n of a closed end for enclosing a heat radiationresponnot directly exposed to the furnace heat. The

jacket I: is provided with a heat shield IS for the comfort of theoperator,'and is pivoted to the Irame M. and provided with acounterpoise I'I, whereby the operator may have-some 'leeway inverticallyaligning the jacket with the slab, other than by verticaladjustment of the frame il.

I Furthernore, the passageway through the jacket sive device, aheat-resisting metal tube enclosing the quartz tube and having 'at leastone side i .opening exposing the quartz tube. and heatextending beyondthe closed end of the quartz tube.

JAMES WARD PERCY. I

quartz tube having a

